I bought a used RadRunner. The disc brakes are prone to warping especially if you transport your bike and lay it on its side. Try not to put excessive weight on the discs. I just fix mine using pliers and manually bending back or forward the warp parts of the disc. It's quite simple and YouTube explains it well.

I did replace the front fork because the previous one was bent. I think this happens when you're going 20mph and hit a curb or sharp bump. Replacement part was $60.

Kickstand spring broke and Rad gave me another for $1 along with nuts and bolts that were missing from the previous owner.

Electric motor and battery is doing fine. I purchased another battery for long rides. Because Rad is so popular there are great/cheap OEM options that other e-bike manufacturers don't have.

I think for the price Rad is amazing if you're willing to tinker with it occasionally.